This invention relates to troughing for molten metals and more particularly it relates to heated troughing for flowing molten metal such as molten aluminum from one station to another.
Conventional troughing used for conveying molten aluminum from a molten aluminum source such as a holding furnace to a work station such as a degasser or caster is either not heated or if heated, utilizes radian heaters such as glow bars which radiate heat from above the surface of the molten metal. If no heaters are used in the troughing, then the distance the metal can be conveyed is limited or the molten metal must be superheated to compensate for the loss in temperature, with its attendant problems such as skim generation. However, radiant heaters have the problem of short service life because they are exposed to aluminum vapors, splashing of molten aluminum and mechanical abuse. Also, radiant heat has the problem that it results in local heating of the surface of the molten metal in the roughing and deposition of a metal skim on the sidewalls of the troughing which contributes to oxide formation. Thus, it can be seen that there is a great need for an improved troughing for conveying molten metal such as molten aluminum which overcomes these problems. This invention provides such an improved troughing.